“Arc discharge” is a phenomenon happened between two electrodes that have a high voltage between them. When the two electrodes are moved gradually and closely to each other at a selected distance, an arch-like electric spark occurs between them that is somewhat like the lightning taking place in the thunderstorm. However the lightning comes and goes in a flash, the spark between two electrodes may exist for a long period of time and may form heat accumulation.
In electronics, arc discharge often damages the function of electronic elements and results in dysfunction of electronic circuits. In serious situations, it even becomes hazardous to the safety of human life. For instance, in conventional high voltage output loads (such as cold-cathode tube, negative ion generator, TV cathode-ray tube and the like), before the load receives a high voltage, if the contact is poor, ambient temperature and humidity varies or some elements of the electronic circuits are ruptured or damaged, the arc discharge happens. Hence how to provide an arc discharge protection apparatus on the potential arc discharge location to prevent the load device from being damaged is one of the key research and development directions in the industry. The commonly used design and elements at present for arc discharge protection apparatus such as voltage boosting device in the conventional high voltage transformer, and ceramic and piezoelectric transformer and the like are elaborated as follows:
Refer to FIG. 1 for the general high voltage transformer or ceramic transformer. It has a constant operation frequency. And a control unit 11 provides a control frequency. Under the alternate mating of these two frequencies, a high AC voltage is generated during the alternate period. A voltage boosting unit 13 has an output end which might form a fracture or a small gap due to poor contact or other unknown reasons. As a result, arc discharge occurs. It is a high voltage arc discharge that directly affects the service life of the surrounding elements. It also indirectly affects the load 14. Therefore an electrical leak protection device 30 is generally being provided. The electrical leak protection device 30 includes an electrical leak switch to protect short circuit that breaks off when the arc discharge takes place. However, the electrical leak protection device 30 usually is used only on small mechanical equipment that have smaller vibrations to ensure that an adequate arc distance is spared in the ejecting direction of the arc. The electrical leak protection device 30 is not suitable to be installed on the location where mechanical vibration is great or alternate magnetic field is strong. Moreover, installation of the electrical leak protection device 30 also has to take into account of the damages resulting from moisture and dust. Hence extra protection measures must be taken. Thus the practicality is lower and installation cost is higher. All this reduces its economic effectiveness.
Refer to FIG. 2 for a voltage boosting unit 13 consisting of a transformer made of piezoelectric plates. The voltage boosting unit 13 includes a transformer (piezoelectric plates) 131 and a circuit board 133 that are connected by a lead 132. There is a coupling location 134 between the circuit board 133 and a load 14. Take an inverter circuit as an example. The factors attributed to arc discharge generation include (1) varying of temperature and humidity causes rupture or poor contact on the lead 132, (2) aging or break down of the transformer (piezoelectric plates), (3) aging or improper use of the coupling location 134 results in a gap between the male plug and female receptacle, (4) the load 14 breaks off. All the foregoing factors could generate an arc discharge signal when a high voltage is output at the output end. In FIG. 2, an arc switch device 40 is provided to receive and channel the arc discharge signal to a ground end. But such a device cannot eliminate all the arc discharge signals. Hence it does not control the operation of the entire circuit. The voltage boosting unit 13 still has residual arc discharge signals due to poor contact, or change of temperature and humidity. Furthermore, during conduction to the ground, the circuit board 133 connected to the transformer (piezoelectric plates) still has arc discharge due to continuous voltage increasing and discharging of the transformer (piezoelectric plates). As a result, heat is accumulated or sparks occur and burn out may happen.
As previously discussed, conventional arc discharge protection apparatus cannot completely prevent arc discharge and have many restrictions. Their applicability is limited.